Package on Package (POP) is an integrated circuit packaging technique to allow vertically combining multiple packages, e.g., discrete logic and memory ball grid array (BGA) packages. Two or more packages are mounted on top of one another, i.e. stacked, with an electrical interface to route electrical signals between them. This allows higher density integrated circuit chips usable in mobile devices, for example in mobile telephones or Personal digital assistants (PDA). However, due to different materials used in the combined multiple packages, the POP structure may have thermal (heat) related issues such as heat dissipation or mismatched thermal expansion coefficients.